<!DOCTYPE html>

<html>
    <head>
        <meta charset="UTF-8">
        <title>清除浮动</title>
        <style type="text/css">
            .wrapper {
                width: 800px;
                border: 1px solid blue;
            }

            .first {
                float: left;
                width: 200px;
                height: 30px;
                background: #dfdfdf;
            }

            .second {
                float: left;
                clear: both;
                width: 400px;
                height: 40px;
                background: #ff0;
            }

            .third {
                float: right;
                width: 200px;
                height: 50px;
                background: rgb(208, 0, 255);
            }

        </style>
    </head>
    <body>

        <h3>"浮动定位"</h3>
        <p>这是一种不务正业的定位方式</p>

        <div class="wrapper">
            <div class="first">天</div>
            <div class="second">地</div>
            <div class="third">玄</div>
        </div>

    </body>
</html>